Gammaherpesviruses are closely associated with the development of lymphoproliferative disease and lymphomas, as well as other cancers. The long-term goal of this research is to understand how gammaherpesviruses manipulate normal B or T cell development to persist within the lymphoid compartment of the infected host. Understanding the mechanisms used by gammaherpesviruses to persist in the infected host may lead to the development of strategies for interfering with chronic infection. The focus of the proposed studies on murine gammaherpesvirus 68 (gHV68; also referred to as MHV-68) represents an ongoing effort to develop a tractable small animal model for characterizing establishment and maintenance of gammaherpesvirus infection. The proposed studies focus on the determining the function of one of the critical latency-associated antigens of gHV68, the M2 antigen. Aim 1. In vivo characterization of gHV68 M2 mutant viruses, 1.a. Role of M2 antigen in the establishment of latency in specific B cell reservoirs; 1.b. Characterization of M2 mutant virus reactivation from B cells in response to a define stimulus; 1.c. Generation of M2-deficient mutants on a replication defective background; and 1.d. Adoptive transfer of gHV68 latently infected naive and memory B cells into uninfected recipient mice. Aim 2. Characterization of gHV68 M2 B cell transgenic mice. 2.a. Generation and initial characterization of M2 B cell transgenic mice; and 2.b. Characterization of B cell development and responses in M2 B cell transgenic mice. Aim 3. Identify and characterize interactions of the M2 antigen with cellular proteins. 3.a. Characterization of M2 antigen interaction with endophilin II and Grb2 in mammalian cells; 3.b. Generation and characterization of M2 mutant viruses that disrupt the interaction of M2 with endophilin II and/or Grb2; and 3.c. Characterization of the impact of M2 antigen expression on growth factor receptor and B cell receptor internalization and signaling.